class Chord:
    
    def __init__(self):
        self.steps = dict() #key(fullNotesList)=>value(number of step)

    def addStep (self, step, note):
        self.steps[note] = step
    
    def containsNote(self, note):
        return note in self.steps
        
    def getStepFor (self, note):
        if not self.containsNote (note):
            return -1
        return self.steps[note]
    
    def getNotes(self):
        return sorted(self.steps.keys(), 
                      key=lambda note: self.steps [note]);
    
    def __eq__(self, other):
        # get steps from map, order, compare values
        return False